Get a cheap, DIY lens hood or flash filter: A lens hood–like the kind you can print yourself–prevents glare, flare, and other light tricks beaming in from just around your lens edges. Similarly, a piece of white coffee filter can work wonders for diffusing your flash, giving bar shots and other low-light situations a much mellower light

DIY Flash diffuser: Milk carton, or if you really need to tone down a flash, yogurt container. That’s what we use for underwater photography when the little diffusers that come with the flashes get lost.

mlange.myopenid.com

I’ve also heard that the semi-opaque film canisters make for great diffusers for pop-up camera flashes. It might have been a MAKE article, even.